LEGUMES AXD GRASSES 



43 



16-year rotation. Greater losses of 

 nitrogen are attributed to corn. 

 Fertilizers, including a combination 

 of nitrogen, phosphorus, and potas- 

 sium, were not effective in decreas- 

 ing nitrogen and organic-carbon 

 losses. 



Olmstead (64) studied the effects 

 of longtime cropping systems on 

 soil aggregation at Hays in 1945. 



Plots studied were on the dryland 

 agricultural project and adjacent 

 fields of the experiment station. 

 Soils were Munjor and Yocemento 

 silty clay loam. He determined 

 the percentage of water-stable 

 aggregates under various cropping 

 systems (table 28). By definition, 

 water-stable aggregates were those 

 larger than 0.2 mm. 



Table 28. — Percentage of water-stable aggregates at 2 depths in experimental 

 fields, Hays, Kans., 1945 l 





Rotation 

 and plot 



Cropping system 



Water-stable aggregates 



larger than 0.2 mm. at a 



depth of — 



Item 

 number 



1 to 5 



inches 



7 to 11 

 inches 





Per- 

 cent 



Stand- 

 ard 

 error 



Per- 

 cent 



Stand- 

 ard 

 error 



1 

 2 



MC-B 



MC-D 



570-D 



MC-D 



560-A 



92-A 



MC-B 



501-A 



591-A 



C-15-7 



C-15-8 



141-A 



141-B 



Range 10__. 



Range 5 



Range 5 



Range 5 



Range 5 



Range 5 



Range 5 



Range 5 



Range 3 



Project 



Winter wheat, early plow 



Winter wheat, fallow. 



9.8 



5.9 



11. 9 



13.4 

 10. 2 



9.8 



10. 5 

 16. 5 



46.6 



31.3 



26.8 



19.7 

 25. 8 

 5.2 

 21.8 

 23.0 

 25. 3 

 14. 7 

 18. 1 

 18. 1 

 17.4 

 12.4 



60.2 

 56. 



1.4 



. 3 



2.7 



1. 

 . 9 



1. 



1. 



.8 



2.0 



1. 2 



1. 5 



1.7 

 1. 5 



. 7 

 1.7 



. 6 

 1. 5 

 1. 1 

 1. 4 

 1. 



.9 



.9 



3.3 

 1. 7 



38.2 

 32. 1 

 46.9 



42.8 

 44.2 



50. 5 



49. 6 

 23. 1 



57.4 



45. 1 



54.5 



58.9 

 55. 5 

 30.6 

 42. 5 

 55. 

 55. 7 



50. 1 

 50.8 

 52.8 

 53.7 

 57.0 



66.9 

 61.8 



3.9 

 2. 



3 



4 

 5 



6 



7 



Winter wheat, fallow, fallow, 



fallow. 



Spring barley, fall plow 



Wheat, kafir, fallow, 12 tons 



manure. 

 Wheat, corn, barley, peas 



(green manure). 

 Kafir, fall plow _ 



1.2 



.8 

 2.7 



1.5 



1.8 



8 



9 



10 



11 



12 

 13 



Fallow, wheat, kafir, plow 14 



inches deep. 

 Wheat, stubbled-in, no tillage, 



29 years. 

 Wheat, stubble burned, no 



tillage, 10 years. 

 Wheat, stubbled-in, no tillage, 



18 years. 



Buffalograss, 1 year 



Buffalograss, 4 vears 



1.3 

 2.2 

 1. 5 

 1. 3 



1.3 



1.7 



14 

 15 

 16 



Weeds, no tillage, 3 years 



Side-oats grama, 7 years 



Blue grama, 7 vears 



2.6 



1.9 

 2. 1 



17 



Buffalograss, 7 years 



1.4 



18 

 19 



Western wheatgrass, 7 years. _ 

 Switchgrass, 7 vears _ 



2.3 

 1.7 



20 

 21 

 22 



23 

 24 



Little bluestem, 7 years 



Big bluestem, 7 years 



Sweetclover, sweetclover, fal- 

 low, 14 years. 



Buffalograss, 28 years 



Native pasture 



1.8 

 2.7 

 3.7 



1.6 

 1.0 











Data from Olmstead (64). 



